With the continued rise of the global incidence of COVID-19 infection and emergent second wave, the need to understand characteristics that impact susceptibility to infection, clinical severity, and outcomes remains vital. The objective of this study was to assess modifying effects of demographic factors on COVID-19 testing status and outcomes in a large, diverse single health system cohort. The Mount Sinai Health System de-identified COVID-19 database contained records of 39,539 patients entering the health system from 02/28/2020 to 06/08/2020 with 7,032 laboratory-confirmed cases. The prevalence of qRT-PCR nasopharyngeal swabs (χ2 = 665.7, p<0.0001) and case rates (χ2 = 445.3, p<0.0001) are highest in Hispanics and Black or African Americans. The likelihood of admission and/or presentation to an intensive care unit (ICU) versus non-ICU inpatient unit, emergency department, and outpatient services, which reflects the severity of the clinical course, was also modified by race and ethnicity. Females were less likely to be tested [Relative Risk(RR) = 1.121, p<0.0001], and males had a higher case prevalence (RR = 1.224, p<0.001). Compared to other major ethnic groups, Whites experienced a higher prevalence of mortality (p<0.05). Males experienced a higher risk of mortality (RR = 1.180, p = 0.0012) at relatively younger ages (70.58±11.75) compared to females (73.02±11.46) (p = 0.0004). There was an increased severity of disease in older patient populations of both sexes. Although Hispanic and Black or African American race was associated with higher testing prevalence and positive testing rates, the only disparity with respect to mortality was a higher prevalence in Whites.